I might have to check maf soon. Mine does this too. Mostly if don't let warm up and leave immediatly once I shift to 2nd and all gears if can make it buck feels like back pressure of fuel almost slapping sound coming from rear. However sometimes happens randomly too when driving seems like not on all cylinders....I have new tank,pump,filter, plugs,wires, dist rotor, alternator,now wp and tsat. When I have run fuel inj cleaner it wakes up a lot and did run prem for bit didn't do as much. Amount of fuel in tank doesn't really matter, temp outside either, mostly seems random.